US12448325B2ActiveUtilityPatentIndex 49
Optical film, sputtering target, and method of producing optical film
Est. expiryNov 25, 2039(~13.4 yrs left)· nominal 20-yr term from priority
Inventors:OKAMI HIDEHARU
G02B 5/208C23C 14/54C23C 14/352C23C 14/3414C23C 14/083C23C 14/0042C03C 2218/156C03C 2218/155C03C 17/3417C01G 41/006G02B 5/282C03C 17/245C23C 14/3407H01J 37/3417H01J 37/3429C23C 14/3485C23C 14/568C03C 2217/734C03C 2217/24C23C 14/08
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Claims
Abstract
Provided is an optical film (a composite tungsten oxide film containing cesium, tungsten, and oxygen), a sputtering target, and a method of producing a film by which film formation conditions can be easily obtained. An optical film of the present invention has transmissivity in a visible wavelength band, has absorbance in a near-infrared wavelength band, and has radio wave transparency, and is characterized in that the optical film comprises cesium, tungsten, and oxygen, in which a refractive index n and an extinction coefficient k of the optical film at each of 300 nm and wavelengths [400 nm, 600 nm, . . . , 2400 nm] specified at 200 nm intervals in a wavelength region from 400 nm to 2400 nm are set within a range between “n-max” and “n-min” made by graphing the maximum value and the minimum value of the refractive index in a wavelength dispersion graph of optical constants shown in FIG. 1 and within a range between “k-max” and “k-min” made by graphing the maximum value and the minimum value of the extinction coefficient in the above wavelength dispersion graph of optical constants.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1. A method of producing an optical film having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency, characterized in that the method comprises:
a first step of repeatedly preparing a plurality of samples of optical films with increased or decreased oxygen content by a sputtering method using a sputtering target composed of a mixture of a cesium source compound and a tungsten source compound and feedback-controlling an oxygen partial pressure of a sputtering film formation atmosphere;
a second step of selecting samples of optical films having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency from the prepared samples of optical films;
a third step of measuring the optical constants (refractive index n and extinction coefficient k) of the selected samples of optical films at wavelengths from 300 nm to 2400 nm by an ellipsometer;
a fourth step of creating a wavelength dispersion graph from the measured multiple optical constants (refractive index n and extinction coefficient k), and determining the minimum and maximum values of the refractive index n and extinction coefficient k of the optical films at each of 300 nm and wavelengths [400 nm, 600 nm, . . . 2400 nm] specified at 200 nm intervals in a wavelength region from 400 nm to 2400 nm from the wavelength dispersion graph, thereby specifying the numerical ranges of the refractive index n and extinction coefficient k listed in Table 10 below;
a fifth step of preparing a plurality of types of samples of optical films by setting a plurality of film formation conditions of the film formation apparatus using the sputtering target in order to determine the film formation conditions of the film formation apparatus that forms an optical film that satisfies the numerical ranges of the refractive index n and the extinction coefficient k described in Table 10 below;
a sixth step of measuring the optical constants (refractive index n and extinction coefficient k) of the prepared samples of optical films at wavelengths from 300 nm to 2400 nm by an ellipsometer to specify samples of optical films whose refractive index n and extinction coefficient k satisfy the numerical ranges shown in Table 10 below;
a seventh step of producing an optical film having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency based on the film forming conditions of a film forming apparatus in which the specified sample of optical film is formed
TABLE 10
nm
n-min
n-max
nm
k-min
k-max
300
2.6
3.2
300
0.3
0.7
400
2.1
2.6
400
0.0
0.2
600
1.9
2.3
600
0.0
0.2
800
1.8
2.1
800
0.0
0.3
1000
1.7
2.1
1000
0.0
0.5
1200
1.7
2.1
1200
0.0
0.7
1400
1.7
2.2
1400
0.1
0.8
1600
1.7
2.3
1600
0.1
0.9
1800
1.7
2.4
1800
0.2
1.0
2000
1.8
2.6
2000
0.2
1.0
2200
1.9
2.7
2200
0.3
1.0
2400
1.9
2.8
2400
0.3
1.0.
2. The method of producing an optical film according to claim 1 , characterized in that
the feedback control of the oxygen partial pressure is performed using an impedance controller which feedback-controls an impedance change during film formation.
3. The method of producing an optical film according to claim 1 , characterized in that
the feedback control of the oxygen partial pressure is performed using a plasma emission monitor which feedback-controls the oxygen partial pressure by measuring an emission intensity at a specific wavelength during film formation.
4. The method of producing an optical film according to claim 1 , characterized in that the sputtering target having a ratio between cesium atoms and tungsten atoms (Cs:W) is 1:2 to 1:4 is used.
5. The method of producing an optical film according to claim 1 , characterized in that the sputtering target composed of a thermally sprayed film of the cesium source and the tungsten source is used.
6. The method of producing an optical film according to claim 1 , characterized in that the compound of the cesium source is an oxide or a carbonate.
7. The method of producing an optical film according to claim 1 , characterized in that the compound of the tungsten source is an oxide or a carbide.
8. The method of producing an optical film according to claim 1 , characterized in that the sputtering target is a cylindrical rotary target.
9. A method of producing an optical film having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency, characterized in that the method comprises:
a first step of repeatedly preparing a plurality of samples of optical films with increased or decreased oxygen content by a dual-sputtering method using a sputtering target of a cesium source and a sputtering target of a tungsten source and feedback-controlling an oxygen partial pressure of a dual-sputtering film formation atmosphere;
a second step of selecting samples of optical films having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency from the prepared samples of optical films;
a third step of measuring the optical constants (refractive index n and extinction coefficient k) of the selected samples of optical films at wavelengths from 300 nm to 2400 nm by an ellipsometer;
a fourth step of creating a wavelength dispersion graph from the measured multiple optical constants (refractive index n and extinction coefficient k), and determining the minimum and maximum values of the refractive index n and extinction coefficient k of the optical films at each of 300 nm and wavelengths [400 nm, 600 nm, . . . 2400 nm] specified at 200 nm intervals in a wavelength region from 400 nm to 2400 nm from the wavelength dispersion graph, thereby specifying the numerical ranges of the refractive index n and extinction coefficient k listed in Table 11 below;
a fifth step of preparing a plurality of types of samples of optical films by setting a plurality of film formation conditions of the film formation apparatus using the sputtering target in order to determine the film formation conditions of the film formation apparatus that forms an optical film that satisfies the numerical ranges of the refractive index n and the extinction coefficient k described in Table 11 below;
a sixth step of measuring the optical constants (refractive index n and extinction coefficient k) of the prepared samples of optical films at wavelengths from 300 nm to 2400 nm by an ellipsometer to specify samples of optical films whose refractive index n and extinction coefficient k satisfy the numerical ranges shown in Table 11 below;
a seventh step of producing an optical film having transmissivity in a visible wavelength band, having absorbance in a near-infrared wavelength band, and having radio wave transparency based on the film forming conditions of a film forming apparatus in which the specified sample of optical film is formed.
TABLE 11
nm
n-min
n-max
nm
k-min
k-max
300
2.6
3.2
300
0.3
0.7
400
2.1
2.6
400
0.0
0.2
600
1.9
2.3
600
0.0
0.2
800
1.8
2.1
800
0.0
0.3
1000
1.7
2.1
1000
0.0
0.5
1200
1.7
2.1
1200
0.0
0.7
1400
1.7
2.2
1400
0.1
0.8
1600
1.7
2.3
1600
0.1
0.9
1800
1.7
2.4
1800
0.2
1.0
2000
1.8
2.6
2000
0.2
1.0
2200
1.9
2.7
2200
0.3
1.0
2400
1.9
2.8
2400
0.3
1.0.
10. The method of producing an optical film according to claim 9 , characterized in that the method comprises:
adjusting an electric power to be applied to a sputtering cathode or a duty ratio such that a ratio between cesium atoms and tungsten atoms (Cs:W) contained in the optical film becomes 1:2 to 1:4.
11. The method of producing an optical film according to claim 9 , characterized in that
the feedback control of the oxygen partial pressure is performed using an impedance controller which feedback-controls an impedance change during film formation.
12. The method of producing an optical film according to claim 9 , characterized in that
the feedback control of the oxygen partial pressure is performed using a plasma emission monitor which feedback-controls the oxygen partial pressure by measuring an emission intensity at a specific wavelength during film formation.Cited by (0)
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